Monday, April 5, 2021

Who cooks for you, barred owl?

barred owlThere are many species of owls in the Adirondacks, with barred owls being the most common, and the most frequently seen.

We mainly hear owls calling between Autumn and early Spring. Great Horned Owls nest earlier than other owls, and their deep staccato HOO-hoo-hoo-hoo-hoo-HOO call, sounding most like the stereotyped call we associate with owls generally, is resonant and vaguely threatening.

The Long-eared owl, which resembles a smaller, perpetually startled and skinny great horned, has a call which reminds you more of song bird calls, stretched out with longer pauses between notes, which may be single syllable “ooo” or raspier pleas, sounding almost cat like. Screech owl calls are shrill and loud, sharp and abrupt. If you ever watched the comedy “My Cousin Vinny”, there is a funny scene where the Joe Pesci character, surprised by a screech owl’s scream in the dead of night, runs out of the cabin firing a pistol, followed by a close up of the screech owl. Tiny saw whet owls make a “toot-toot” call, like a small truck backing up. 

Barred owls tend to be monogamous, and we begin hearing the male territorial come-mate-with-me calls in November. The barred owl call is nearly conversational, and is well captured by the phrases, “Who-cooks-for-you? … Who-cooks-for-you-all?” Barred owls are large owls, smaller than Great Horned, but much larger than the other three mentioned above, and more often spotted by hikers and nature lovers, roosting by day in the open, less hidden, though sometimes blending into their background, and flying away upon approach. While Great Horned owls have a more forbidding appearance, Barred owls have rounded heads, framed by an uneven light brown streak dipping between the eyes, which have inner borders of concave swirls of bristle feathers, which protect the eyes and as part of the facial disk, help direct sound to the ears.  Barred owls range from brownish with whitish-gray horizontal bars to deep grayish with similar bars, hence the name. Barred owls look almost pleasant and are generally more tolerant of human presence.

Male barred owls defend territories of about 700 to 1,000 acres in a variety of habitats, ranging from mature conifer to deciduous forests, or the mixture of the two, and the males and females call back and forth with some frequency. Compared with lively courting raptors, such as red-tailed hawks, with their spinning and talon-clutching aerial acrobatics, owls seem almost comically serious. Still, preliminary courtship displays, even for established barred owl mates, are extensive, with females making raspy, noisy calls, and males responding, often with sliding along a branch, while spreading the wings, bobbing and weaving, sort of like an out-of-shape Michael Jackson, still trying to look cool.

barred owl chickWhile barred owls may maintain several nesting sites within a territory, for backup in case of natural disaster, human activity or predator attacks, the male will try to secure the same nest used the previous year, which might be a crevice or hole in a tree, a previously used nest in a snag, an abandoned squirrel nest, or even a human-built box, preferably from 20 to 40 feet above the ground. 

Once they establish that they are still a couple, nesting begins in February, and the female will lay between one and five eggs, over a period of several days, with a hatching period of 28 to 33 days. Chicks are covered in a fine down and start begging for food shortly after hatching. The chicks born first are larger in size, and tend to dominate their smaller siblings during feeding, which is why starvation may reduce a clutch to a pair of older fledglings. In fact, if no members of a clutch survive, barred owls may nest again, and produce a second clutch.

Female raptors are about a third larger on average than males, which may make it more efficient for Mom to incubate the eggs with her larger bulk, while drawing on her fat reserves when the male, who brings all the prey during the first two weeks after the chicks start hatching, can’t keep up with the demand, at a time of rapid growth rate for the chicks. Her larger size also makes her better armed to fight off attacks by their number one enemy, the Great Horned Owl, as well as goshawks and raccoons. 

Fledglings begin branching at about 4 or 5 weeks, crawling up out of the nest, awkwardly perching on nearby branches, spreading and closing their wings, all in preparation for testing those wings. Many first flights fail, with the fledge twisting and flopping down like a failed kite, in which case they will try to use their beak and talons to climb back up the tree to the nest. When that does not work, Mom and Dad will feed the fledge on the ground until the fledge flies, starves or a predator comes across them. Surviving fledges fly at about ten weeks but are fed by Mom and Dad through most of the Summer. You may spot fledges in the Spring, and they’ll look large and raggedy with the oversize flight feathers nature provides to help the first-year owls get around the relative lack of mature flight muscles. Their flight will be anything but smooth, as they try to make their way around.

Barred owl remains, meaning owls which are structurally and genetically indistinguishable from modern barred owls, go back about 11,000 years, from Ontario, Florida, and Ohio. As bird skeletal bones are hollow, they’re a great aid in flight, but tougher to preserve for paleontological finds, so this is a pretty rough guess. There are three Northern Barred Owl sub-species generally recognized, the Texas, Florida and Mexican.

In the Adirondacks, Barred owls, members of the Strix genus, are exceeded in size only by their number one enemy, the Great Horned Owl, which in my humble opinion, may be the greatest predator, pound-for-pound, and feather-for-feather that ever lived. Thank natural selection we’re large, and they’re only 4 or 5 pounds. Barred owls average about 21 inches long, with a weight of about 1.6 pounds, and a wing span of about 43 inches.  Snowy Owls are heavier, Great Grays are larger, but both of these owls are seasonal, infrequent visitors, while neither Barred Owls or Great Horned Owls even migrate. 

Birds of prey don’t migrate because of the cold. Feathers are much more efficient at heat retention than mammalian fur. Birds of prey migrate because of the relative lack of access to hibernating or snow concealed prey in Winter, or in the case of the occasional snowy owl down here in the Adirondacks, an explosion of lemmings far north on the tundra, resulting in many more snowy chicks than usual surviving the nesting phase, thereby exceeding the carrying capacity for adult snowies up there, and forcing many young snowies to find other territories.

The barred owl has “higher wing loading”, which means they typically listen for prey from a perch, say the branch of a tree, or the top of a road sign, and then dive down to seize the prey. Raptor which catch moving prey while flying are said to be “lower wing loading”, such as peregrine falcons or osprey

All of these owls share certain predatory advantages in common, which include exceptional hearing ability. Barred owls have asymmetrical ears, meaning one ear is higher on the skull than the other, and larger in size. This gives barred owls the ability to triangulate prey position, as sounds from prey activity land on one ear micro seconds before the other. When you add to this feature the fact that owls’ eyes can not move within the skull sockets, it means that to triangulate prey position, they swivel their heads enough – up to 270 degrees! – for the sounds to arrive at both ears simultaneously, meaning by definition, they are staring at the location where the prey has to be. When you see owls bobbing their heads, they may be compensating for the fact that their eyes are immobile, and bobbing gives them different angles and perspectives.

The eyes are long, tubular and, and in terms of photoreceptors, have many more rods than cones, which means owls detect the slightest motion, and because their heads are round, wide and without the ear tufts found on Great Horneds, Screech owls and Long eared owls, which break up the head’s outline, and because they have 14 neck vertebrae, twice the number people have, they may swivel their heads without having to move their bodies, it would be very difficult for prey to notice them. While most owls have yellow eyes, the eyes of barred owls are so dark brown, they are nearly black.

It gets scarier. Owls feature silent flight, so their prey probably will not detect their approach. Most birds, particularly larger birds like water fowl, tend to be noisy in flight. Think about it. We hear the geese before we see them. Owls tend to have larger wings relative to body size, which enables them to fly and glide more slowly than other birds of prey. In addition, owls have softer flight feathers, which feature tiny comb like serrations on the lead edge, as well as soft fringes on the outer edge, which combined, break up the air turbulence which produces most of the sounds of flight. Silent flight gives owls the added advantage of not interfering with their attempts to hear the movements of their prey while flying.

barred owlWhen they perch, the barred owl’s four toes tend to be in a three-in-the-front, one-in-the-rear configuration, enabling them to grasp the branch. But their outer toe is opposable, like your thumb. The owl continues to triangulate as it dives, fine-tuning the prey’s location, and just before they reach their prey, they swivel the outer talon to the rear, into a 2 x 2 configuration, so that upon feeling the small mammal’s spine, they can simply squeeze, crushing the prey, often resulting in instant mortality. 

Owls as a group tend to have larger, more powerful talons than raptors of similar size. Barred owls go after any small mammals from mice and voles to rabbit, and even smaller skunks, kittens or puppies.  Barred owls can fly, carrying prey twice their weight. Be very careful when you let small pets out. Best to keep near them. Don’t gross out over the skunks. Birds of prey have a very attenuated sense of smell, so skunk may be a delicacy. Barred owls are very opportunistic, and will grab snakes, frogs and lizards, and some wade into water to grab fish and crayfish. Barred owls who have perfected going after crayfish, develop a reddish tinge to their feathers.

Owls lack crops, which other birds use to store food for later consumption. At the same time, they have no teeth, so they can’t chew their food, and they cannot digest bone, feathers or fur. Prey are usually swallowed whole, or brought back to the nest to be dismembered by beak and talon, and then shared. The owls digestive system is composed of two parts: the smaller proventriculus produce enzymes, mucus and acid, which begin the digestive process, while the next stop, the larger venticulus or gizzard, separates the indigestible parts, forming a pellet, which is stored in the proventriculus before being regurgitated by the owl, about ten hours later. The owl cannot swallow prey again, until the pellet is ejected, and these pellets are in great demand by kids visiting the Wildlife Refuge, who will then dissect them in the class room to see what the owl has been eating. Barred owls live up to 24 years in the wild.

Barred owls are highly successful predators who have been gradually expanding out west into the territory of the Spotted Owl in the northwest and Northern California. The spotted owl looks like a slightly smaller barred owl, and barred owls have been hybridizing spotted owls by mating with some, but also killing others, so spotted owl populations are declining within their native territory, while barred owl populations are increasing. 

Barred owls are more efficient predators and can make a living in smaller territories than can spotted owls, so spotted owl ranges can support a higher number of barred owls. Wildlife managers have been experimenting with lethal control of Barred owls in Spotted owl territory, to determine whether killing barreds will result in a rise in Spotted populations. I go back and forth on the issue but would never claim to be a qualified expert. It does seem to me that what is happening might be called “Natural Selection”, and I sometimes wonder whether we believe in evolution, just not on our watch.

Spotted owls were threatened back in the nineties by old growth forest logging, a debate that went to the Supreme Court, where old growth logging was restricted, while putting Spotted Owls on the Endangered Species List and the cover of Time Magazine. Wendy and I like to vacation out in the Northwest and the San Juan Islands, as well as Vancouver Island and the Great Bear Rain forest of B.C. We were briefly on the Olympic Peninsula looking for black bears and Roosevelt elk, while this debate was raging, but we noticed on the lighter side, that loggers, who have arguably the most dangerous of outdoor jobs, were making a safer living taking tourists around wilderness areas they know better than anyone. A great novel about logging in the northwest is “Sometimes a Great Notion”, by Ken Kesey.

Top photo by Dr. Bharath Manu, barred owl chick photo by Anne Fraser and photo of Wendy Hall holding an owl by  Joe Kostoss, of Eye in The Park. All images courtesy of Adirondack Wildlife Refuge

 

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Steve Hall

Steve and Wendy Hall run the Adirondack Wildlife Refuge and Rehab Center in Wilmington. They've been rehabbing and releasing wild animals for over 45 years, specialize in predators, keep wolves as the cornerstone of their educational program, and have lived in the Adirondacks for the past 20 years. The Adirondack Wildlife Refuge became a non-profit about 10 years ago.

Visit www.AdirondackWildlife.org to learn more.


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18 Responses

  1. Phil Fitzpatrick says:

    Great article, thank you, Steve.

  2. Phil Fitzpatrick says:

    Postscript…. I believe that it is not rare for young owls to starve to death in their first winter. They may hang out near a bird feeder looking for prey. Maybe you can offer some suggestions as to how people can feed and help these youngsters.

    • Boreas says:

      Phil,

      Some owls will respond to our discarded chicken/turkey carcasses placed in a spot that the birds frequent. But even then, I doubt it is too healthy for them with our salt/chemical injected meats. If you find fresh roadkill, that might be a healthier alternative for these birds. They will certainly respond to pet store mice and lab mice/rats – both living and dead. Just make sure they are safe for consumption.

      An interesting experiment is to buy or borrow a game/trail cam and set it up to observe a carcass in you back yard or wooded area. You may be surprised to learn the nocturnal and unseen creatures near or on your property. I have had one set up just into the trees at the edge of my “lawn” along a tiny brook that also serves as a game trail. Fox, coyotes, fisher, weasels, raccoons, ‘possums, turkeys, and the ubiquitous deer and squirrels all are regularly seen. Still no bear or bobcat, but I have not given up hope!

  3. Boreas says:

    Great article Steve!

  4. Allen FITZGERALD says:

    Last year, my early-spring garden was devoured by voles, field mice, and baby rabbits that can fit through the holes in my fencing. I wish I had a Barred Owl or two to prey upon them. Steve mentions placing nests for them 20 to 40 feet up. Where can I get details about such nests? And what kind of tree(s) do they prefer?

  5. JT says:

    A few years ago, I was sitting in a tree stand. I saw a Bard Owl in a tree about 30 yards away. The Owl flew over to a tree five yards in front of me and landed on a branch facing the other way. Then it turned it’s head 180 degrees looking straight at me. We had a staring contest for a minute and then it went on it’s way. That made my day.
    Then, just last year, we were camping in a lean-to on Cranberry Lake. Just after dark, we had one high up in a tree watching us. They seem to exhibit a curiosity of people.

  6. Vanessa Banti Vanessa says:

    Awesome article, thanks Steve! For those who aren’t watching yet, the Cornell barred owl cam is delightful. Eggs should hatch this week-ish, and mom has been doing great. Although no one cooks for her, since she swallows her prey whole!

    We had a great horned owl family in our local park, but they seem to have moved on due to excessive attention from onlookers. I have to admit, I too was super excited and often pointed my long lens camera. Mom seemed to get tired of us all gawking at her. It can be challenging to value nature while also having very little impact.

  7. Mark says:

    Living in a heavily wooded area, we hear then daily. Love sleeping with the windows open at night, as they call to each other. Also helpful with moles and voles.

  8. Jeff Waterman says:

    This is a really great, informative article!

  9. Jackie Woodcock says:

    This is great!! Never really thought about owls until being at the Refuge! Fell in love with all the animals!

  10. JT says:

    Was watching Northwoods Law on TV last night. Someone in NH called in a Bard Owl beside the road thinking it got hit by a car. The conservation officer who responded checked out the owl and it did not appear to have any injuries, but he noted that it felt very thin when he picked it up. He brought it to a wildlife rehabilitator and they determined that it was starving and did not have the energy to fly. The rehabilitator said she currently was rehabilitating over 50 Bard Owls due to starvation. It had to do with the harsh winter they just had and inability for the owl’s to obtain food. I thought this was interesting, something to keep in mind in the future if I ever see a Bard Owl on the ground in the late winter or spring time.

  11. Charlie Stehlin says:

    Actually ‘Bard’ is very fitting for the owl as there is most certainly poetry in their voices!

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